From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: Ilya Maximets <i.maximets@samsung.com>,
dev@dpdk.org, tiwei.bie@intel.com, zhihong.wang@intel.com,
jfreimann@redhat.com, nicknickolaev@gmail.com,
bruce.richardson@intel.com, alejandro.lucero@netronome.com
Cc: dgilbert@redhat.com, stable@dpdk.org,
"Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [dpdk-stable] [PATCH v2 01/17] vhost: fix messages error checks
Date: Wed, 3 Oct 2018 16:39:23 +0200 [thread overview]
Message-ID: <e2843403-5782-94f9-4b48-da7198e593cd@redhat.com> (raw)
In-Reply-To: <20181003090454eucas1p180d79e1279ca4e1086b2447758686978~aDeOgna1t0120201202eucas1p1W@eucas1p1.samsung.com>
On 10/03/2018 11:07 AM, Ilya Maximets wrote:
> On 03.10.2018 11:32, Ilya Maximets wrote:
>> On 03.10.2018 11:02, Maxime Coquelin wrote:
>>>
>>>
>>> On 10/03/2018 09:57 AM, Ilya Maximets wrote:
>>>> On 03.10.2018 10:50, Maxime Coquelin wrote:
>>>>>
>>>>>
>>>>> On 10/02/2018 04:15 PM, Ilya Maximets wrote:
>>>>>> On 02.10.2018 12:36, Maxime Coquelin wrote:
>>>>>>> Return of message handling has now changed to an enum that can
>>>>>>> take non-negative value that is not zero in case a reply is
>>>>>>> needed. But the code checking the variable afterwards has not
>>>>>>> been updated, leading to success messages handling being
>>>>>>> treated as errors.
>>>>>>>
>>>>>>> Fixes: 4e601952cae6 ("vhost: message handling implemented as a callback array")
>>>>>>>
>>>>>>> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
>>>>>>> ---
>>>>>>> lib/librte_vhost/vhost_user.c | 6 +++---
>>>>>>> 1 file changed, 3 insertions(+), 3 deletions(-)
>>>>>>>
>>>>>>> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
>>>>>>> index 7ef3fb4a4..060b41893 100644
>>>>>>> --- a/lib/librte_vhost/vhost_user.c
>>>>>>> +++ b/lib/librte_vhost/vhost_user.c
>>>>>>> @@ -1783,7 +1783,7 @@ vhost_user_msg_handler(int vid, int fd)
>>>>>>> }
>>>>>>> skip_to_post_handle:
>>>>>>> - if (!ret && dev->extern_ops.post_msg_handle) {
>>>>>>> + if (ret != VH_RESULT_ERR && dev->extern_ops.post_msg_handle) {
>>>>>>> uint32_t need_reply;
>>>>>>> ret = (*dev->extern_ops.post_msg_handle)(
>>>>>>> @@ -1800,10 +1800,10 @@ vhost_user_msg_handler(int vid, int fd)
>>>>>>> vhost_user_unlock_all_queue_pairs(dev);
>>>>>>> if (msg.flags & VHOST_USER_NEED_REPLY) {
>>>>>>
>>>>>> Maybe we need to reply here only if we didn't reply
>>>>>> already (not VH_RESULT_REPLY) ? Otherwise, we could
>>>>>> reply twice (with payload and with return code).
>>>>>
>>>>> Well, if the master sets this bit, it means it is waiting for
>>>>> a "reply-ack", so not sending it would cause the master to wait
>>>>> forever.
>>>>>
>>>>> It is the master responsibility to not set this bit for requests
>>>>> already expecting a non "reply-ack" reply (as you fixed it for
>>>>> postcopy's set mem table case).
>>>>
>>>> vhost-user docs in QEMU says:
>>>> "
>>>> For the message types that already solicit a reply from the client, the
>>>> presence of VHOST_USER_PROTOCOL_F_REPLY_ACK or need_reply bit being set brings
>>>> no behavioural change.
>>>> "
>>>> i.e. even if QEMU sets the need_reply flag, vhost should not reply twice.
>>>> Am I missing something?
>>>
>>> Oh, right. Thanks for pointing it out.
>>>
>>> So coming back to the DPDK implementation, I just had a look again, and it seems that we don't send a reply twice, as send_vhost_reply takes
>>> care of clearing the VHOST_USER_NEED_REPLY flag.
>>> Do you confirm my understanding is correct?
>>
>> Hmm. Yes, you're right. send_vhost_reply clears the VHOST_USER_NEED_REPLY
>> flag and vhost doesn't send replies twice.
>> Maybe some comment with clarifications needed here, or some more
>> refactoring to make this aspect more clear.
>>
Agree.
I'm adding a comment, I don't think a refactoring is required, and I
would be reluctant to add one more refactoring so close to the
integration deadline.
Does it work for you?
Thanks,
Maxime
next prev parent reply other threads:[~2018-10-03 14:39 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-02 9:36 [dpdk-stable] [PATCH v2 00/17] vhost: add postcopy live-migration support Maxime Coquelin
2018-10-02 9:36 ` [dpdk-stable] [PATCH v2 01/17] vhost: fix messages error checks Maxime Coquelin
2018-10-02 14:15 ` Ilya Maximets
2018-10-03 7:50 ` Maxime Coquelin
2018-10-03 7:57 ` Ilya Maximets
2018-10-03 8:02 ` Maxime Coquelin
2018-10-03 8:32 ` Ilya Maximets
2018-10-03 9:07 ` Ilya Maximets
2018-10-03 14:39 ` Maxime Coquelin [this message]
2018-10-04 5:42 ` Ilya Maximets
2018-10-02 9:36 ` [dpdk-stable] [PATCH v2 02/17] vhost: fix return code of messages requiring replies Maxime Coquelin
2018-10-03 13:26 ` Ilya Maximets
2018-10-03 14:49 ` Maxime Coquelin
2018-10-04 5:49 ` Ilya Maximets
2018-10-02 9:36 ` [dpdk-stable] [PATCH v2 03/17] vhost: fix error handling when mem table gets updated Maxime Coquelin
2018-10-02 9:36 ` [dpdk-stable] [PATCH v2 04/17] vhost: define postcopy protocol flag Maxime Coquelin
2018-10-02 9:36 ` [dpdk-stable] [PATCH v2 05/17] vhost: add number of fds to vhost-user messages and use it Maxime Coquelin
2018-10-02 9:36 ` [dpdk-stable] [PATCH v2 06/17] vhost: pass socket fd to message handling callbacks Maxime Coquelin
2018-10-02 9:36 ` [dpdk-stable] [PATCH v2 07/17] vhost: enable fds passing when sending vhost-user messages Maxime Coquelin
2018-10-02 9:36 ` [dpdk-stable] [PATCH v2 08/17] vhost: add config flag for postcopy feature Maxime Coquelin
2018-10-02 9:36 ` [dpdk-stable] [PATCH v2 09/17] vhost: introduce postcopy's advise message Maxime Coquelin
2018-10-02 9:36 ` [dpdk-stable] [PATCH v2 10/17] vhost: add support for postcopy's listen message Maxime Coquelin
2018-10-02 14:11 ` Ilya Maximets
2018-10-03 7:46 ` Maxime Coquelin
2018-10-02 9:36 ` [dpdk-stable] [PATCH v2 11/17] vhost: register new regions with userfaultfd Maxime Coquelin
2018-10-02 9:36 ` [dpdk-stable] [PATCH v2 12/17] vhost: avoid useless VhostUserMemory copy Maxime Coquelin
2018-10-02 9:36 ` [dpdk-stable] [PATCH v2 13/17] vhost: send userfault range addresses back to qemu Maxime Coquelin
2018-10-02 9:36 ` [dpdk-stable] [PATCH v2 14/17] vhost: add support to postcopy's end request Maxime Coquelin
2018-10-02 14:18 ` Ilya Maximets
2018-10-02 9:36 ` [dpdk-stable] [PATCH v2 15/17] vhost: enable postcopy protocol feature Maxime Coquelin
2018-10-02 9:36 ` [dpdk-stable] [PATCH v2 16/17] vhost: add flag to enable postcopy live-migration Maxime Coquelin
2018-10-02 9:36 ` [dpdk-stable] [PATCH v2 17/17] net/vhost: add parameter to enable postcopy support Maxime Coquelin
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